What is Asystole?
A cardiac arrest occurs when the heart stops effectively pumping blood around the body. This causes immediate unconsciousness and breathing to stop.
The heart is controlled by co-ordinated electrical activity (this is known as sinus rhythm). When a cardiac arrest occurs, the heart goes into a different electrical rhythm.
Some of these electrical rhythms can be treated by delivering an electrical shock to the heart. This is called defibrillation. Common ‘shockable’ rhythms include Ventricular Fibrillation (VF) and Ventricular Tachycardia (VT).
So what is asystole?
Asystole occurs when there is a lack of any electrical activity in the heart. This means defibrillation will not be successful.
On a monitor, asystole is often described as being a flat line. However, in practice, the line is not completely flat. There is, however, a lack of any electrical activity on the monitor. The trace below shows an example of asystole.
How is asystole treated?
Unfortunately, it is not possible to use a defibrillator when the heart is in asystole. This is because there is no electrical activity in the heart.
The only treatment for asystole is effective CPR, use of Advanced Cardiac Life Support (ACLS) drugs and treating any reversible causes of cardiac arrest.
The outcomes for patients with an asystolic cardiac arrest are very poor and unfortunately, CPR is unlikely to be successful, but should still be attempted.